Drove another 355 today, same spec as mine and.....

What exhaust do you have...and what exhaust was on the car you drove?

 

Cam timing during the belt service makes quite the difference

 

Cam timing is off.

 

There are NO changes (that I know of) with "Sport mode". It only stiffens the shocks a little bit. Listen to the others here about power differences.

 

Sometimes odometers are not indicative of mechanical conditions. I would say to check cam timing, general tune up items such as spark plugs airfilter fuel filter. Also dirty maf. 02 sensors (check for obd codes.) Etc.

The suspension sounds like it could have a different ecu or your shocks are weak. It should tighten up in sport. Does ur suspension light work . (separate from sport light )

 

My 99 f1 was night and day regular from sport. 95, not so much but it is stiffer by default and softer when button cycled.

 

Cam timing and general tune up are most likely the differences. The F355 has ITB's as well and synchronizing them at a major service is important. I don't know your service records but many low mile cars have gone a long duration between important services compared to cars regularly driven and with more miles.

 

Perhaps you should get a compression test or leak down test performed on yours. If that comes up OK then get a full engine out service and, as stated previously, the cam timing set up properly at the same time.

 

Is your bypass valve functioning? Also check to see if you are getting wide open throttle. (When I received my previous 355 it was only getting 3/4 throttle due to cable adjustment)

 

Can't repeat cam timing enough, the procedure is complicated and often I'm told you can end up with each bank slightly different than each other and it's critical to get them to synchronized.

-Michael

 

Some engines dyno more power than others regardless of what the factory numbers are. In Aston martin v12 it is not uncommon to see large variation in performance by two otherwise well running cars.

 

If you really think there is a problem, take the car somewhere and have it properly diagnosed. Otherwise, dive it and enjoy it and don't worry about what the seat of your pants tells you.

 

My car was underperforming and I found the throttle linkage had shifted and it was only giving 75% travel..

 

Bad gas?

 

fouled injectors with plenty gunk inside due to low mileage.

 

Maybe clean out the combustion chambers with a double-dose of BG44k or Techron?

Newer tires will make a ~big~ difference in overall handling. To a lesser degree, also refreshed bushings.

+1 on checking the throttle travel. That is a 30 second job with the Mrs. in the passenger seat. Just reach under the coolant tank when the pedal is on the floor and try to rotate the bell crank further counter-clockwise. If it moves at all, it needs adjustment (they also commonly stick on WOT but that is another thread).

For a change in behavior, the difference may be faulty (re: 15 year-old) dampers which need oil and nitrogen replacement and shaft refurbishment (see Bilstein or Delta-Vee rebuild services).

Good luck.
Ken

 

Have you had your engines compression tested recently?

From what I've seen with the inspections I've done on some low mile cars, it really doesn't matter if the cars been beat and not operated properly. 115psi across the board with 35% leak down on a 16k mile car...try and figure that one out.

 

Can you say valve guides. Not much to figure out. My car with 15,000 miles needed the guides done, but I budgeted that into my purchase price and once done I know its done.

 

Might want to adjust your Vtec controller.

 

The car I mentioned had the valve guides done at 11k miles...5k miles later same problem. Previous owner used bronze guides. Probably why it was for sale...owner didn't want to fork out another 20k.

 

In order of likelihood::

Compression
Injectors
Ignition
Cam Timing

 

Could be clutch pressure, wear. My 98 355F1 GTS was feeling sluggish, even at highway speeds. Clutch adjustment by Competizione made a world of difference.

 

That, or change the VTEC fluids.

 

How often do I need to change the VTEC belt?